public class Program
{
    public static void Main(string[] args)
    {
        DataTable data = new DataTable();

        Dictionary<string, Dictionary<string, int>> users = new Dictionary<string, Dictionary<string, int>>();

        foreach (DataRow row in data.Rows)
        {
            string cBsUnit = row["cBsUnit"].ToString();
            for (int i = 0; i < row.ItemArray.Length; i++)
            {
                row[i].ToString().Split(',').Where(p => !string.IsNullOrEmpty(p)).ToList().ForEach(k =>
                {
                    if (users.ContainsKey(k))
                    {
                        if (!users[k].ContainsKey(cBsUnit))
                        {
                            users[k].Add(cBsUnit, i);
                        }
                    }
                    else
                    {
                        users.Add(k, new Dictionary<string, int> { { cBsUnit, i } });
                    }
                });
            }
        }

        var a = users.ToList();
        a.GroupBy(p => p.Value);
    }

    public void GetMessage(Dictionary<string, int> a)
    {
        string[] message = new string[5];

        foreach (var item in a)
        {
            if (item.Value <= 5)
            {
                if (string.IsNullOrEmpty(message[4]))
                {
                    message[4] = ">15天";
                }
                message[5] += item.Key + "  " + 0;
                if (item.Value <= 5)
                {
                    
                }
            }
        }
    }

}